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How police use DNA ‘familial searches’ to probe murders

Investigators are using DNA analysis and basic genealogy to find relatives of potential suspects, in the hope that these “familial searches” will crack cold cases.
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Investigators are using DNA analysis and basic genealogy to find relatives of potential suspects, in the hope that these “familial searches” will crack cold cases.
By

WASHINGTON

It’s a forensics technique that has helped crack several cold cases. Across the country, investigators are analyzing DNA and using basic genealogy to find relatives of potential suspects in the hope that these “familial searches” will lead them to the killer.

Familial searches led California authorities to arrest Joseph James DeAngelo in the Golden State Killer probe in April, and investigators have since used it to make breakthroughs in several other unsolved murder cases, including four in Washington state, Pennsylvania, Texas and North Carolina.

But as these searches proliferate, they are raising concerns about police engagement in “DNA dragnets” and “genetic stop and frisk” techniques. And as public DNA databases grow and are accessed by law enforcement, investigators may soon have the ability to track down nearly anyone, even people who never submitted their genetic material for analysis.

“If you are a privacy zealot, this is super alarming. It means you don’t have any privacy,” said Malia Fullerton, a bioethics specialist and professor at the University of Washington. “On the other hand, if you have no problem with police using your family information to solve these cold cases, you might see this as a good thing.”

Part of the concern stems from law enforcement’s rapid embrace of familial searches to investigate crimes, aided by open-access DNA databases that did not exist a decade ago.

One of these is Florida-based GEDmatch, founded in 2010. GEDmatch allows genealogy enthusiasts to upload and share their DNA profiles, created from commercial services such as Ancestry and 23andMe. The site offers special tools to help find people find relatives, and since it is free of charge, it has rapidly grown — to more than 920,000 profiles by May.

It’s also proven to be a gold mine for law enforcement.

In California’s Golden State Killer probe, investigator Paul Holes turned to GEDMatch after trying to find a match for DNA the killer left at a Ventura County crime scene. Holes initially looked through the FBI’s DNA database, which includes genetic profiles of people arrested or convicted of crimes, but he came up empty.

To broaden his search, Holes registered with GEDmatch using an alias, uploaded the unknown suspect’s DNA profile. Several distant relatives of the suspect came up. Investigators then spent months building family trees and tracking down relatives using basic genealogical reserach, to narrow their list of possible suspects.

Ultimately they arrested DeAngelo, a former police officer living outside of Sacramento.

Investigators were lucky that at least one of DeAngelo’s distant relatives had shared their DNA profile on GEDmatch. But the methods police employed in their search are coming under scrutiny.

Before identifying DeAngelo, investigators reportedly assembled and examined 25 different family trees, possibly involving up to 1,000 people. Only one of these family trees ended up containing the alleged serial rapist and murderer. But now investigators had information on all those other people.

Investigators initially zeroed in on two suspects other than DeAngelo, and even went so far as to gain a court warrant to sample DNA from one of them, a 73-year-old man in an Oregon nursing home, by force if necessary. But neither he nor another man had DNA that matched the crime scene sample.

In a recent commentary, Fullerton and collaborator Rori Rohlfs argued that the Golden State Killer probe demonstrated how innocent bystanders can be ensnared through familial searches.

“These details, many of which only came to light after intense press coverage, raise a host of concerns about the methods employed (by police) and the degree to which they exposed otherwise innocent individuals to harms associated with unjustified privacy intrusions,” they wrote in Leapsmag, an online magazine focused on the life sciences.

Researchers say it won’t be long before investigators can track a wide swath of the U.S. population, at least those of European descent, using familial searches.

In a study this year, Columbia University geneticist Yaniv Erlich and other scientists examined DNA data for 600,000 people of European heritage, and found that, in half of their searches, they could find a match with a third cousin or closer relative. “In the near future virtually any European-descent US person could be implicated by this technique,” the researchers wrote in their paper, currently under journal peer review. Open-access DNA databases have a higher proportion of samples from people of European descent.

In California, investigators have used familial searching for several years to catch rapists and murderers, including the “Grim Sleeper” Lonnie Franklin Jr., convicted in 2016 of ten serial killings. But the technique has skyrocketed in popularity following DeAngelo’s arrest.

These cases and others were aided by CeCe Moore, a genetic genealogist now working with Parabon NanoLabs, a DNA technology company in Virginia. Moore has a hero to crime victims nationally and a media celebrity. She appeared this month on NBC’s “Today Show” extolling the potential of familial DNA searching and the work of Parabon, which has become a go-to service for law enforcement nationwide.

“I think we can make society a safer place, and hopefully even cause someone to stop and think — maybe it could be a deterrent,” Moore said.

Investigators are increasingly turning to open-access databases because the limitations of existing FBI and state databases. Since these databases only contain genetic information for people arrested or convicted of crimes, they aren’t representative of the U.S. population as a whole, and may not include DNA of unknown serial killers.

A detailed tally of serial killers worldwide maintained by Radford University in Virginia — now numbering 5,031 dating back to the 1900s — shows that 12.9 percent U.S. serial killers had never been arrested before starting their murder sprees, according to Michael Aamodt, a retired Radford professor who launched the tally.

For investigators, federal and state DNA databases present other limitations. Unlike GEDmatch, many of these were originally designed to aid law enforcement in making direct genetic matches, not the partial ones used in familial searching. In addition, California and other states have enacted restrictions on using their law enforcement databases for familial searching, partly out of privacy concerns. Maryland and Washington D.C. have passed laws forbidding such use.

Given the reach of familial searching through GEDmatch and similar sites, some legal experts say the time has come for government regulation of these sites and how law enforcement uses them.

Exploitation of GEDmatch “raises the question what kind of end runs police allowed to do around our current database system, without any kind of oversight at all,” said Erin Murphy, a law professor at New York University who wrote a book on forensic DNA.

Ariel Deray, a Florida lawyer familiar with DNA cases, said that many consumers submit their genetic information to GEDmatch and other sites with little awareness that third parties, including the police, might seek to access it. “These services have become exponentially popular in such a short period of time, but the laws haven’t caught up,” said Deray, an associate in the Fort Lauderdale office of Saul Ewing Arnstein & Lehr.